Each wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (PDA), pager, personal computer (PC), laptop computer, home entertainment equipment, etc., either includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). Radio transceivers are currently being integrated, in System-on-Chip (SoC) or System-in-Package (SiP), to reduce cost, size, and power, and to increase functionality. One consequence of this integration is reduced test access to the radio system's functional blocks (e.g., individual transmitter and receiver blocks). Traditionally, radio transceiver testing has relied on separate testing of each transmitter and parallel testing of multiple receivers. Thus, receiver testing has generally enjoyed the benefits of reduced test time and reduced test cost. However, with the integration of transmitters and receivers onto a single chip, the ability to test multiple receivers in parallel does not result in a decrease in test time or test cost of integrated transceivers.
For example, modulation accuracy of a transmitter is typically measured by a precision receiver, while demodulation accuracy of a receiver typically uses a test signal generator (source). Both the precision receiver and the precision source are expensive test instruments. Although a single precision source can simultaneously stimulate multiple transceivers, a precision receiver is only capable of measuring the output of one transceiver at a time. Therefore, attempting to test multiple transceivers in parallel would not result in a corresponding decrease in test time or test cost, because one precision receiver test instrument is still required per transceiver device under test (DUT).
Therefore, what is needed is a test system that allows transceiver modulation error to be tested on multiple transceiver devices in parallel without increasing the number of test instruments in proportion to the number of transceivers being tested.